Ms li has 4 different books and 1 red pen,1 blue pen and 1 black pen she is wrapping one book and one pen. draw a tree diagram to find the number of combinations she can choose.

You are remodeling your kitchen. you’ve contacted two tiling companies who gladly told you how long it took their workers to tile of a similar size jim completed half the floor in 8 hours. pete completed half of the other floor in 7 hours. if pete can lay 20 more tiles per hour than jim, at what rate can jim lay tiles